The present invention concerns beans which contain flatulence-causing sugars, and more specifically, methods of processing such beans that remove flatulence-causing sugars while leaving most of the protein content intact.
Beans are a source of protein which has not been utilized yet to the extent it might. One reason why other sources of protein are sometimes preferred over beans is the gastrointestinal stress they can cause.
This distress is the result of the presence of certain sugars in beans, such as raffinose, stachyose, and verbascose. Enzymes such as .alpha.-galactosidases and .beta.-D-fructosidases are needed to hydrolyze these sugars so they can be absorbed in the digestive tract. However, humans do not have those enzymes, so the sugars listed above are not absorbed. Instead, they are fermented by microorganisms in the intestines, producing flatus.
Several methods have been developed for removing flatulence-causing compounds from soybeans, a different type of beans than the ones contemplated for processing in accordance with the present invention. It is not clear whether the soybean processes will be useful for the types of beans contemplated by the present invention.
One category of soybean processes involves hot water treatment and aqueous alcohol extraction to insolubilize most of the protein in soybean meal. This method has the disadvantage that the protein is damaged in the process of being insolubilized. Also, one process in this category requires ethanol, a fairly expensive chemical, as a solvent.
Another soybean process involves protein extraction from soy flour or soy flakes and precipitation of protein from the extract by acid treatment. These procedures are relatively time-consuming and expensive, and generate whey as a by-product which contains a significant amount of protein and other valuable constituents. Soybeans have also been treated by enzymatic hydrolysis of the flatulence-causing sugars. The products of this group of processes are not known to have achieved commercial use. Some of the products produced by such processes have exhibited unacceptably high flatus activity and have also had low flavor acceptability.
Yet another category of soybean processes employs soaking and fermentation. However, this method is not believed likely to lend itself to large scale processing. One final method of processing soybeans involves germination, but the beneficial effects claimed for this process have not been clearly proven. Some researchers have observed flatulence reduction after germination, while others have not observed any such reduction. Soybeans have also been treated for the purpose of removing flatulence-causing sugars using hollow fiber reactors which contain immobilized enzymes. However, these processes operate on a soy milk, and there appears to be little commercial incentive to develop flatus-free soy beverages. These processes also have cost disadvantages because of the enzymes used as well as the necessity of protein extraction and clarification.
There is a need for methods of removing flatulence-causing sugars from beans that would leave most of the proteins intact. Such methods could produce bean products that would be more useful in meeting the nutritional needs of the world.